INS and type 1 diabetes mellitus: Consistent with this hypothesis, it is well established that a genetic polymorphism (variable number tandem repeat, VNTR) in the promoter region of the human insulin gene alters susceptibility to type 1 diabetes, that class I (short-repeat) VNTR alleles are strongly associated with increased risk of developing type 1 diabetes [45, 46], and that class I alleles also are associated with an increased insulin gene transcription rate in pancreatic beta cells [47].